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KVM: MIPS: Support NetLogic KScratch registers
tlbex.c uses the implementation dependent $22 CP0 register group on NetLogic cores, with the help of the c0_kscratch() helper. Allow these registers to be allocated by the KVM entry code too instead of assuming KScratch registers are all $31, which will also allow pgd_reg to be handled since it is allocated that way. We also drop the masking of kscratch_mask with 0xfc, as it is redundant for the standard KScratch registers (Config4.KScrExist won't have the low 2 bits set anyway), and apparently not necessary for NetLogic. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Radim Krčmář" <rkrcmar@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org
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@ -91,6 +91,21 @@ static void *kvm_mips_build_ret_from_exit(void *addr);
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static void *kvm_mips_build_ret_to_guest(void *addr);
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static void *kvm_mips_build_ret_to_host(void *addr);
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/*
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* The version of this function in tlbex.c uses current_cpu_type(), but for KVM
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* we assume symmetry.
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*/
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static int c0_kscratch(void)
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{
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switch (boot_cpu_type()) {
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case CPU_XLP:
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case CPU_XLR:
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return 22;
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default:
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return 31;
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}
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}
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/**
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* kvm_mips_entry_setup() - Perform global setup for entry code.
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*
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@ -105,18 +120,18 @@ int kvm_mips_entry_setup(void)
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* We prefer to use KScratchN registers if they are available over the
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* defaults above, which may not work on all cores.
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*/
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unsigned int kscratch_mask = cpu_data[0].kscratch_mask & 0xfc;
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unsigned int kscratch_mask = cpu_data[0].kscratch_mask;
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/* Pick a scratch register for storing VCPU */
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if (kscratch_mask) {
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scratch_vcpu[0] = 31;
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scratch_vcpu[0] = c0_kscratch();
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scratch_vcpu[1] = ffs(kscratch_mask) - 1;
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kscratch_mask &= ~BIT(scratch_vcpu[1]);
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}
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/* Pick a scratch register to use as a temp for saving state */
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if (kscratch_mask) {
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scratch_tmp[0] = 31;
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scratch_tmp[0] = c0_kscratch();
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scratch_tmp[1] = ffs(kscratch_mask) - 1;
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kscratch_mask &= ~BIT(scratch_tmp[1]);
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}
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@ -132,7 +147,7 @@ static void kvm_mips_build_save_scratch(u32 **p, unsigned int tmp,
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UASM_i_SW(p, tmp, offsetof(struct pt_regs, cp0_epc), frame);
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/* Save the temp scratch register value in cp0_cause of stack frame */
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if (scratch_tmp[0] == 31) {
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if (scratch_tmp[0] == c0_kscratch()) {
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UASM_i_MFC0(p, tmp, scratch_tmp[0], scratch_tmp[1]);
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UASM_i_SW(p, tmp, offsetof(struct pt_regs, cp0_cause), frame);
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}
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@ -148,7 +163,7 @@ static void kvm_mips_build_restore_scratch(u32 **p, unsigned int tmp,
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UASM_i_LW(p, tmp, offsetof(struct pt_regs, cp0_epc), frame);
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UASM_i_MTC0(p, tmp, scratch_vcpu[0], scratch_vcpu[1]);
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if (scratch_tmp[0] == 31) {
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if (scratch_tmp[0] == c0_kscratch()) {
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UASM_i_LW(p, tmp, offsetof(struct pt_regs, cp0_cause), frame);
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UASM_i_MTC0(p, tmp, scratch_tmp[0], scratch_tmp[1]);
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}
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